In a number of gas-heated appliances, usually for households, it is common for a manufacturer to provide two different nozzle assemblies so that a nozzle with a first restriction may be used if the household is equipped to burn liquefied petroleum gas, or LPG, and a second nozzle assembly with a less restricted outlet if the household is equipped to use natural gas in the gas appliance. This is due to the lower BTU content of natural gas compared with LPG to achieve the same rate of BTU output of the gas appliance.
In many cases, the two alternative gas nozzle assemblies are ones wherein the gas to the nozzle comes through a conduit, a cap is fitted onto the end of the conduit, and the cap holds in place either one of two different inserts which have different size openings for the two types of gas. Once installed, the other insert often gets lost so that it becomes difficult to convert the appliance to the other type of gas. Also, merely assembling the proper insert in the nozzle assembly by a householder may be most difficult for one with arthritic fingers, for example, and often the gas nozzle assembly is in a relatively inaccessible space within the gas appliance.